Using the FrontEnd
User Tags Configuration
User Tags are derived from ordinary SNMP variables, in most cases,
implementing special calculations to obtain performance indicators
based on raw SNMP data.
User Tags List
To manually add a User Tag, you can use the
Add Tag button on the top toolbar. Alternatively, you can
right-click any empty space in the Tag View and select
Add Tag from the context menu.
You can edit properties of a particular tag by either selecting it
on the list and clicking on the Tag Properties button on
the top toolbar or right-clicking the tag and choosing
Tag Properties from the context menu.
Both options(adding or editing a User Tag item)
will display a detailed tag configuration dialog box.
Tag Add/Remove Toolbar
You can customize the following item settings:
-
Tag Name: The name of the tag.
-
Description: A textual description of the displayed value of
the tag.
-
Expression: The expression used to calculate this tag. You can
edit this field clicking on Edit Expression
button.
-
1st Order Filter: Check to create an additional tag (with
"_Filtered" in the name) that applies a low pass filter in this
item. This is only available for numerical variables.
The User Tag Properties Dialog
To edit the Expression, click on Edit Expression
button.
The Expression Wizard will open. In the first step, define
the expression using variables, in example you see the utilization
formula:
utilization = ( ( 8 * ( delta(a) +
delta(b) ) ) * c ) * 100
You can use up to eight variables to construct your own expression.
Note that latin characters are not allowed to variable names.
The four basic operations - addition( + ), subtraction(
- ), multiplication( * ) and division( / ) -
and the delta function. This function calculate the delta of the
specified variable:
delta(x) - calculate the difference between the
current x value and the last saved value.
You can group expression parts using parentheses, simplificating
the human reading and changing the formula interpretation: a + b /
c is different from (a + b) / c.
During expression edit, a validator will be executed below the
expression box. If "The expression is invalid" text is
show, an error was found and the formula needs to be revised.
Then, in step two, define the SNMP OID for each
variable. Note that each variable is associated with a
SNMP OID, so if device MIB Tree
changes, all User Tags must be checked for changes
too.
You can search for a tag in Tag List in the right of the
dialog. This list is loaded from RAW Tags List, so it's
recommended that you scan the device for MIB-II OIDs before
creating/editing User Tags.
To simplificate the search task, you can use the Look for
filter at top of the Tag List. Type a match expression for
SNMP MIB column and all tags will be filtered.
Then drag-and-drop the selected tag to the specified variable.
Calculation Expression Wizard
To change the SNMP OID of a variable, drag a new
OID to it.
To finish this Wizard and save the new expression, click on the
Finish button.
Note that you must enable and configure your SNMP device before
setting up traps in the server.
After editing or adding the tag, click on the OK button to
close the User Tag Properties dialog and update the item
settings. If you want to discard all changes, just click the
Cancel button to close the dialog.
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